Field of Invention
Embodiments of the present disclosure generally relate to transmission of digital information. In particular, the present disclosure relates to a channel encoder configured to transform information sequence into a discrete encoded sequence/codeword.
Description of the Related Art
The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
With increasing popularization of mobile communication, communication services with only voice service can not satisfy the demands for information collection anymore, and mobile data communication service has exhibited huge and promising prospect with its more convenient and more abundant information content e.g. business and entertainment. Therefore, high speed packet access services that support high speed data transmission, especially high speed downlink packet access (HSDPA), and Long Term Evolution (LTE), from a base station to a user terminal, among other technologies, have become one of key targets of future wireless communication systems.
In the operation of a wireless communication system, a transmitter device transmits a signal containing useful data to a receiver device over an air interface. In multiple-input multiple-output (MIMO) wireless communication systems, signals are transmitted over multiple parallel paths by way of multiple transmit antennas and/or multiple receive antennas. A MIMO system takes advantage of the spatial diversity and/or multiplexing provided by multiple parallel antennas to improve the signal-to-noise ratio (SNR) of the combined received signal and increase data throughput without increasing bandwidth usage. MIMO has many benefits including improved spectrum efficiency, improved bit rate and robustness at cell edge, reduced inter-cell and intra-cell interference, improvement in system capacity and reduced average transmit power requirements. Error correcting codes are commonly used in wireless systems to protect against bit errors in received signals caused by channel fading, interference and receiver defects. Typically, an encoder adds redundancy information to user data prior to transmission, and a corresponding decoder is applied to the received signal to recover the original data.
FIG. 1 illustrates an exemplary block diagram 100 showing a typical flow path for transmission/storage of digital information, wherein data transfer can be initiated from an information source 102 to a destination 118 (or user). The information source 102 can be either a person or a machine, for example, a digital computer, or a data terminal, wherein source output, which is to be communicated to the destination 118, can be either a continuous waveform or a sequence of discrete symbols. A source encoder 104 can be incorporated in the transmission flow to transform the source output into a sequence of binary digits (bits) referred to as information sequence, which, in case of a continuous source, can involve analog-to-digital (A/D) conversion. The source encoder 104 can be designed such that the number of bits per unit time required to represent the source output is minimized, and the source output can be unambiguously reconstructed from the information sequence.
A channel encoder 106 can also be incorporated to transform the information sequence into a discrete encoded sequence, commonly referred to as a codeword, wherein, in most instances, the encoded sequence is a binary sequence, although in some applications non-binary codes are also used. The codeword can then be sent from a modulator 108 through a channel/storage medium 110 to a demodulator 112, which can pass the codeword to a channel decoder 114 for onward processing by a source decoder 116, and finally sent to the destination 118.
Existing systems and implementations of channel encoder 106 need to combat with a noisy environment in which the codewords must be transmitted or stored, which is a problem that has been not been efficiently and effectively solved as yet. In a communication system, it is actually impossible to receive a transported signal without any distortion or noise. In particular, when the signal is transported/received over a wireless network, the effects of the distortions (e.g. due to multipath, shadowing, etc.) or noises are more serious as compared with when the signal is transported/received over a wired network.
Many efforts have been made to minimize the effects of the distortions or noises. An error control coding technique has been proposed as a typical method of minimizing the effects of the distortions or noises. Codes used for the error control coding technique are classified into memory-less codes, and memory codes, wherein each memory-less code includes a linear block code, while the memory code includes a convolutional code and a turbo code. A device for generating such codes is called a “channel encoder”, and its output can be divided into systematic bits and parity bits based on the error control coding technique. The turbo code is a code typically used for the error control coding technique that separates its outputs into the systematic bits and the parity bits. In addition to the turbo code, there exists a systematic convolutional code of the convolutional code as a code used for the error control coding technique. Herein, the “systematic bits” mean an actual transport signal, while the “parity bits” mean a supplemental signal added to correct a possible error, which occurred during transportation in a decoding process. However, even though a signal is subjected to the error control coding, if a burst error occurs in the systematic bits or the parity bits, it is not easy to correct the burst error. Such a phenomenon frequently occurs while the signal passes through a fading channel, and an “interleaving” technique is typically used to prevent this phenomenon. The interleaving technique disperses a damaged part in several places rather than concentrating it on a single place, thereby complementing the error control coding technique.
There is therefore a need in the art to develop a channel encoder that enables efficient handling of noisy environment and improves system performance.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.